[gmx-users] How to increase the tolerance for conjugate gradient minimization
lindahl at cbr.su.se
Sat Jun 19 23:02:50 CEST 2010
It's a pretty fundamental result on numerical analysis that you can only achieve a tolerance that is sqrt(EPS), where EPS is your floating-point accuracy. If you need better tolerance you might have to try double precision.
Be careful to use e.g. switched interactions and a cutoff buffer, and you might want to emply L-BFGS minimization in the endgame.
However: this assumes you really need extremely low tolerance - the only normal application where that is the case is normal modes.
On Jun 4, 2010, at 7:54 PM, Arthur Roberts wrote:
> Hi, all,
> Is there a way to increase the tolerance for Conjugate Gradient energy minimization?
> It seems that I can only get a Tolerance (Fmax) = 1e-4
> emtol doesn't seem to do the trick. I tried several values.
> Much appreciated,
> Dr. Arthur Roberts, Ph.D.
> University of California, San Diego
> Skaggs School of Pharmacy and Pharmaceutical Sciences
> 9500 Gilman Drive #0703
> La Jolla, CA 92093-0703
> email: aroberts99163 at yahoo.com
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Erik Lindahl <lindahl at cbr.su.se>
Professor, Computational Structural Biology
Center for Biomembrane Research & Swedish e-Science Research Center
Department of Biochemistry & Biophysics, Stockholm University
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